Ever since breaking the Australian 1500m record as a 20-year-old back in 2010, huge things have been expected of Gregson.

Longstanding foot injuries stalled his progress for several years.

He made a huge breakthrough two years ago in Rio when he became the first Australian man in four decades to contest an Olympic 1500m final.

Now his focus is firmly set on a podium finish at the April 4-15 Commonwealth Games.

Gregson did it the hard way at the national trials at Carrara Stadium on Sunday.

Stuck on the inside in seventh spot with only 200 metres to run, it would have been easy to panic.

But Gregson stayed calm, pulled wide and mowed down the half-dozen runners ahead of him to win a third straight national 1500m title in three minutes 39.66 seconds.

Runner-up and training partner Jordy Williamsz (3:39.85) also locked in automatic selection for the Games.

The third discretionary spot in the 1500m is likely to go to 800m winner Luke Mathews.

"I really had to stay patient - I felt good the whole way so I just had to wait," said Gregson.

"You've just got to try and stay relaxed.

With 200 to go you probably think it is a very stressful situation but I knew I had another gear.

"When I am 100 per cent and I'm not sick, when my feet aren't sore, I know I can run really well.

"Unfortunately at the world champs last year I was sick and had a broken foot, that's why I raced poorly.

"When I am 100 per cent I am hard to beat.

"I think I will be a lot better in two months time."

At the conclusion of the four-day trials at Carrara Stadium on Sunday, 57 able-bodied athletes had met the automatic selection criteria, with selectors still to chose a further 31.

The home team of 111 will also include 23 para-athletes.

The final squad will be announced Thursday, with chairman of selectors Dion Russell predicting there could be several appeals from aggrieved athletes who miss the cut.

Australian Associated Press